Panaeolus axfordii Y. Hu, S.C. Karunarathna, P.E. Mortimer & J.C. Xu, 2020

Hu, Yuwei, Mortimer, Peter E., Karunarathna, Samantha C., Raspé, Olivier, Promputtha, Itthayakorn, Yan, Kai, Xu, Jianchu & Hyde, Kevin D., 2020, A new species of Panaeolus (Agaricales, Basidiomycota) from Yunnan, Southwest China, Phytotaxa 434 (1), pp. 22-34 : 26-27

Panaeolus axfordii Y. Hu, S.C. Karunarathna, P.E. Mortimer & J.C. Xu , sp. nov. ( Figure 1 )

Index Fungorum number: IF556818, Faces of Fungi number: FOF 06525

Etymology:—the species epithet ‘axfordii’ refers to the renowned mushroom photographer Stephen Axford.

Holotype:— China, Yunnan Province, Kunming, Kunming Botanical Eastern Garden (25 o 08’N, 102 o 44’E), elev. 1916m, with three specimens collected and examined, 12 June 2018, Samantha C. Karunarathna, KIB 1 ( MFLU 19-2367 holotype!).

Diagnosis:—a reddish brown patch at pileus surface center.

Description: Pileus 0.6–0.8cm in height, 1.6–2.1cm in diameter, hemispherical to campanulate; surface dry, glabrous, with a reddish brown (9E7) patch at center; scales present; margin greyish white (1B1) and not striate. Context 1.5– 3mm thick, readily bruising bluish. Lamellae adnate, moderately crowded, 3 tiers, thin, mottled dark grey (1F1), with white (1A1) serrate margin. Stipe 4.2–5.1 cm in height, 1.5–2.5mm thick, cylindrical curved, hollow, surface striate glabrous, annulus absent, grey (1B1) or greyish orange (6B4) toward the apex, light brown (7D6) to brown (7E5) overall, with white (1A1) basal mycelium. Spore print black, not bleaching in concentrated sulphuric acid.

Basidiospores 8.8–11.4 × 6.3–9.0 μm, average 9.8 × 7.6 μm (n=20) in frontal view, average 8.6 × 4.9 μm (n=20) in side view, average 8.2 × 5.5 μm (n=20) in top view, Q F = 1.30, Q S = 1.80, Q T = 1.52, non-transparent, limoniform in frontal view, ellipsoid in side view, smooth, thick-walled, brown (5F6). Basidia 10.5–24.3 × 8.4–13.7 μm (n=20), broadly clavate to obovoid, 4-spored, unclamped. Cheilocystidia 14.4–25.4 × 7.5–10 μm (n=10), utriform to broadly utriform, never bifid, hyaline, thin-walled. Hymenophoral trama subregular. Pleurocystidia not seen. Pileipellis an intricate trichoderm. Pileocystidia 54.1–132 × 3.8–16.7 μm (n=10), narrowly utriform, few bifid. Stipitipellis a interrupted hymeniderm. Caulocystidia 24.6–42.7 × 5.9–10.7 μm (n=10), narrowly utriform, never bifid, hyaline, thin-walled. Clamp connections present but inconspicuous in all tissues ( Figure 1 ).

Habitat and distribution: gregarious on a lawn rich in organic matter, Kunming, Yunnan Province, China.

Notes:—Pleurocystidia were not seen under the microscope, scales present at the pileus center, margin greyish white and not striate ( Figure 1 a,b ). Panaeolus bisporus (Malençon & Bertault) Ew. Gerhardt (1996: 41) and Panaeolus cyanescens (Berk & Broome) Sacc (1887: 1123) have the most similar macro- and micro-morphological characteristics to Panaeolus axfordii ( Table 2) however P. bisporus is 2-spored while P. axfordii is 4-spored; basidiospores of P. cyanescens are bigger than those of P. axfordii . P. bisporus and P. cyanescens belong to subgenus Copelandia Bres (1912: 51) . The subgenus Copelandia comprises P. bisporus , P. cyanescens , P. cambodginiensis , and other possible species, according to phylogenetic analysis from recent research ( Ma 2014), and the subgenus Copelandia is a wellsupported clade within the genus Panaeolus , which is accordance with previous studies ( Gerhardt 1996, Wartchow et al. 2010, Silva-Filho et al. 2018). According to the results of our study, P. axfordii is a distinct new species that belongs to the subgenus Copelandia .

Figures

FIGURE 1. Panaeolus axfordii sp. nov. a, b- Basidiocarps in their natural habitat; c- Basidiospores under SEM; d-Basidiospores under compound microscope; e- Basidia; f- Cheilocystidia; g- Pileocystidia; h- Caulocystidia. Scale bars: c, 4μm; d, 10μm; e, 10μm; f, 10μm; g, 25μm; h, 10μm. Photos by: Samantha C. Karunarathna and Yuwei Hu.